Hexane elimination from soybean oil by continuous packed tower processing with supercritical CO2

Hexane elimination is the most energy-consuming step-in the industrial extr action of soybean oil. It utilizes three sets of equipment: two evaporation stages in series followed,by a stripper at a pressure of about 0.07 bar. T he final hexane residue in the oil is about 1000 ppm. We propose an alterna tive to the present process for hexane elimination, based on the extraction of the soybean oil/hexane mixture with supercritical CO2 in a continuous c ountercurrent packed tower. In this work, we tested a soybean oil/hexane mi xture feed containing 10% by weight of hexane. Various pressures and temper atures of the column were tested to reduce hexane residue in the oil. The e xtraction process was demonstrated to be very effective for hexane separati on. Indeed, at the bottom of the column we recovered soybean oil containing quantities of hexane as low as 20 ppm when we operated at 120 bar, 40 degr ees C. The effect of process parameters is also discussed.